Prevalence of suboptimal peak inspiratory flow rates in users of dry powder inhalers with Chronic Obstructive Pulmonary Disease: a cross-sectional study

Aim: Inhaled medication is considered first line treatment in Chronic Obstructive Pulmonary Disease (COPD). Adequate peak inspiratory flow rate (PIFR) is required for drug dispersion with dry powder inhalers (DPI). A suboptimal PFIR can compromise distal drug deposition and consequently disease control. The objective of this study was to determine the prevalence of PIFR discordance and associated clinical factors in COPD outpatients. Methods: Observational and cross-sectional study including 71 outpatients with COPD, aged 40 years or more, of a family health unit in northern Portugal. Inclusion criteria were the use of a DPI in the last four weeks and no exacerbations in the previous six weeks. PIFR was measured using the In-Check™ Dial®. Participants were classified as discordant if measured PIFR was lower than the considered optimal for the prescribed DPI device.Results: The median age of the participants was 71,4 ± 10,5 years. 59,2% were male, 40,8% were non-smokers and all were caucasian. At the time of assessment, GOLD classification was mainly graded B (59,2%). Suboptimal PIFR was observed in 23 (32,4%) patients. Age (t=-3,303,p<0,05), height (t=4,003, p<0,05) and COPD Assessment Test (CAT) (t=-2,118, p<0,05) were significantly associated with suboptimal PIFR. There was also an association with sex (X2= 5,646, p<0,05) and smoke (X2= 6,477, p<0,05). Patients with suboptimal PIFR were mostly women (60,9%) and non-smokers (60,9%).Conclusions: Suboptimal PIFR was present in nearly 1 in 3 outpatients with COPD and was more frequent in females, non-smokers, with higher CAT results, short stature and older patients. These results suggest that many COPD patients don’t generate adequate inspiratory force to overcome prescribed DPIs resistance in the course of normal use, which may have consequences in disease control. Implementation Science/Service Development Research Ideas on Respiratory Conditions and Tobacco Dependency Abstract Declaration of Interest Boehringer-Ingelheim provided In-Check™ Dial®, having no other participation in the study. Authors have no potential conflicts of interest. References and Clinical Trial Registry Information